A High-Strength Weldable Stainless Steel for Elevated-Temperature Service

Based on considerations of hot cracking, tensile, rupture, and creep strength, high-temperature stability, and oxidation resistance, a chromium-nickel-manganese-molybdenum stainless steel strengthened with boron, zirconium, vanadium, and nitrogen was developed. Although rupture and creep strength reached maxima at a level of about 0.17 per cent nitrogen, yield and tensile strength increased linearly with nitrogen to considerably higher levels. Working temperature and reductions and heat treating temperaturs had major effects on the properties. Tungsten-inert-gas welding has been used to join fabricated plate of this alloy into tubing and elbows used for steam-turbine reheat pipe. The nominal composition of this alloy, called Kromarc 58 steel, is 16 per cent chromium, 20 per cent nickel, 10 per cent manganese, 2.25 per cent molybdenum, 0.2 per cent vanadium, 0.25 per cent silicon, 0.01 per cent boron, 0.01 per cent zirconium, 0.04 per cent carbon, 0.17 per cent nitrogen, and balance iron.